


Bone Daddy

by Aerychan



Category: Undertale (Video Game)
Genre: Adopted Sibling Relationship, Adult Frisk, Angst, Daddy Kink, Divorce, F/M, Fluff, Post-Undertale Pacifist Route, Teacher-Student Relationship
Language: English
Status: Completed
Published: 2018-07-04
Updated: 2018-07-04
Packaged: 2019-06-05 12:14:27
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,813
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15170549
Author URL: https://archiveofourown.org/users/Aerychan/pseuds/Aerychan
Summary: Years have passed since Frisk completed the True Pacifist route and freed her monster friends. Starting a new life as a family with Toriel and Sans had been a dream come true until the mysterious return of Asriel and Chara threw their peaceful lives into turmoil. Now with her adoptive parents in the process of splitting and the beginning of her college career approaching quickly, feelings for the skeleton monster she'd grown to see as a father figure begin to arise until she starts to question whether they're truly so wrong...





	Bone Daddy

~~~~~~~~~~~

She just didn’t get it…

 

Maybe it was because she was still young but Frisk couldn’t understand how someone could just fall out of love after so long. If one betrayed the other or did something else they thought unforgivable, it would make sense.

 

But she'd seen Toriel and Sans fall hopelessly in love nearly a decade ago when they first met in person. She'd been there through the courting and had even helped with Sans's proposal. It had been simplistic and sweet. A corny knock-knock joke that had Toriel in tears but not from laughter.

 

They seemed perfect for each other.

 

Although it took a lot of work on her part as a child to be ambassador for the monster's acceptance and equal rights, it had been worth the struggle. For a long time no one took her seriously and had even tried to remove her from Toriel's care. Thank god for Sans. Though it didn’t help the image humans had painted of evil child-eating demons, he wouldn't let anyone lay a finger on her. She didn't have anyone to go home to anyway..

 

Within a few years, Toriel was legally allowed to adopt Frisk. Not to say she didn't already think of her as her mother or Sans as her self proclaimed ‘duncle', but it was a relief to know that now no one could separate them now.

 

Everything had been perfect. The wedding. Their marriage. Their two story house in the woods at the base of Mount Ebbot. Both monsters were able to get teaching jobs in the city, Toriel at the elementary school and Sans as the AP science teacher for the high school. They had breakfast together every morning, Toriel packed their lunches, then in the evening after dinner they all relaxed in front of the TV until bed time.

 

Papyrus had lived with them for a short while after the barrier fell. Then after a chance meeting with Mettaton, who’d been making a name for himself and was looking a bodyguard/cohost, he found himself employed and moved into his own place, much to Sans's dismay. The brothers had never lived under separate roofs so the distance unnerved the elder skeleton, especially in a world that was still new. Toriel assured him that Papyrus would be fine and his old room would always be open to him.

 

But it wasn't too long after that things started to change drastically and their family of three was thrown into disarray.

 

It was a Saturday morning and Frisk was sitting on the floor, shoving soggy cereal into her mouth and watching the news while Toriel worked on her needlepoint. The forecast predicted the day to be sunny, slightly cloudy with a high of 65 degrees. Sans had said if the weather stayed nice they would go for a picnic

 

The ring of the egg timer in the kitchen had the female monster disappearing into the kitchen before the next news segment began. Moments later the shouts of her adopted child had her rushing back in. At first she was displeased to see the up-turned bowl of milk and mushy cereal on the carpet, but when she looked to the tv she forgot anything else in the world existed.

 

The face of her mother's ex husband in the press was nothing new. He was still king after all and had shared the spot light with her for many events and interviews throughout the campaign for monster rights. His feelings for his former queen were still apparent though, but obviously not reciprocated. Once Frisk was able to focus on school full time, Toriel had been happy to limit his involvement in their lives to the occasional appearance on tv.

 

But no one could've anticipated the pair that joined him on screen that day.

 

Asriel and Chara.

 

A few days prior, the guards watching over the cavern leading out from the Underground had retrieved two individuals and brought them to their king. No one could explain the how or why of their state. Asriel hadn't reverted back to a flower and Chara was…human again. As far as they could see anyways.

 

After the initial shock wore off, panic had set in and Frisk was shouting for Sans. He’d teleported downstairs in an instant, weary from sleep but on high alert with the lights in his sockets dilated. His eyes darted from his dumbstruck wife, to Frisk’s concerned expression, then finally the tv.

 

The look on his face when he turned back to Frisk held a tense understanding. After leaving the Underground she had lost her ability to Reset. Asriel didn’t have the power anymore either after she fell. So what about Chara? If she did, then everything they had worked so hard for in this timeline was at risk.

 

Of course, that had been the furthest thing from Toriel’s mind. Not even a possibility as only Sans and Frisk knew of the danger. After her husband caught her mid-faint, the goat monster rushed to the kitchen without another word, calling every contact she had to get a hold of Asgore.

 

Within a few days their lives were turned upside down. Toriel and Asgore had managed to agree on custody of their children, surprisingly leaving Sans out of the negotiations. Initially it hadn't bothered him too much, but finding out that his wife would be letting Chara into their home, sparked the first of many disagreements to follow.

 

The first few months had been horrible. So many sleepless nights and arguments until it became apparent that Chara didn’t have any power. That didn't stop her from being a little terror at home or at school. 

 

If it wasn't cruel remarks or threats to Frisk and other students, it was pulling hair, shoving, and just overall bullying. All of which she got away with either from intimidation or because Toriel was their teacher. Frisk would wake up some nights with the other child standing over her bed just staring down at her blankly, her hazel eyes seemingly tinged with red light. 

 

This resulted in countless nights on the couch with Sans. The only time she felt safe. Toriel refused to acknowledge or punish her behavior, telling them that they were overreacting. She would say that Chara was just acting out because she missed Asriel and she never misbehaved with Asgore. But anytime Sans suggested she just stay with the king instead, another fight would break out between them. 

 

Frisk had lost count of how many times she sat at the top of the stairs listening to the shouting. For the longest time she resented Chara, not just for their ordeal underground, but for ruining the first family she’d had in a while.

 

Eventually Sans relented, suggesting therapy, counselling, anything it would take to make things work out for them. It was difficult at first, especially after Chara was diagnosed with ‘mild’ sociopathy, but eventually Frisk and Chara were able to find common ground and before long they had formed a bond which seemed to be what the ‘first’ child had needed all along. They weren't as close as she was with Asriel but after a few years the three of them had developed a cohesive sibling relationship.

 

Now the two girls were both seniors in high school, on the cusp of graduation. Honestly Frisk was a certainty while Chara could care less. The other girl hadn’t changed too much and truthfully, if her adopted father wasn't a political figure she would’ve been expelled long ago.

 

Her presence and behavior still put a strain on Sans and Toriel's relationship. While their mother insisted he at least try to establish his own bond with Chara, the skeleton refused which had been just fine by her. When the other human went away every other weekend to be with Asgore and Asriel there was some reprieve, but in the last few years Frisk had given up on hoping things would ever go back to the way it used to be. 

 

And speaking of Asgore…

 

Toriel's tune had changed quite a bit in regards to him after their children returned. With Asriel being the heir to the monster throne, they agreed that he should stay with his father to learn his duties to his people and the politics required when dealing with human leaders. Before long, alternating weekends became weekly dinners and then conjoined family outings.

 

At first, it wasn’t so bad. A little awkward sure, but Sans and Asgore were friends and they would try to make things work out for the children’s sake and to make Toriel happy. But over time Sans stopped coming with them, the weekly dinners moved to Asgore’s place without him, and eventually Frisk felt too uncomfortable to keep going either. As much as they tried to make her feel like part of the family, she just didn’t feel right without the skeleton present.

 

These days Sans barely joined them for meals anyway, opting for coffee in the morning before taking off for work and leaving before dinner once he finished any work he’d brought home. He usually didn't return until after the rest of them were in bed already, less than sober and making a bee line for his recliner where he would fall asleep himself. Frisk was in his last class of the day so at least she got to see him before he would bring her and Chara home via shortcut.

 

Worst of all, he hardly ever made jokes anymore and the ones he did make, obviously for her benefit, were so strained she would have to force her own laughter. She missed his quick witted puns, watching weekend cartoons together, and ‘letting’ him read bed time stories to her when he started to miss Papyrus. 

 

She missed her ‘duncle'….She missed her best friend.

 

Heaving a sigh, Frisk slid her earbuds back in and turned up the music to block out the shouting, trying to focus on her homework. This one was becoming more common. Toriel was angry because Chara was failing some of her classes and if she didn't crack down before finals, she wouldn't be graduating at all. Sans refused to help her, because one: Chara didn’t give a shit and two: she wasn't his responsibility. 

 

As far as he was concerned, Frisk was the closest thing he had to a kid of his own since his and Toriel's magic turned out to be incompatible for offspring and he would never look at Chara as anything more than an unwanted stepchild. Frisk used to feel bad for her, but knew that Chara felt the same. The other human resented all authority figures, Toriel included. She called Asgore ‘dad’, but she didn't even care for him that much either. As long as she was with Asriel or Frisk, she was content.

 

Then just when Frisk thought she was going to get some work done, a shining lump of silver flew into her line of sight, landing on the notebook she’d been writing equations in. Looking towards her doorway, she met the mischievous gaze of her ‘sister’ leaning against the frame, palming a handful of more foil wrapped chocolates. Resisting an exasperated groan, she placed the treat between her teeth and closed her books, plucking the earbuds out once more and flopping back onto her pillows. She didn’t even flinch when Chara slammed her door shut behind her and practically dive bombed the open side of the bed.

 

Truth be told, they didn’t even talk more than what was necessary. They read each other well enough to have a grasp of what the other was thinking and what their mannerisms meant. Like how throwing her favorite edible substance at you was Chara’s way of offering comfort. Therapy and support from her siblings had helped with her sociopathy to a degree, but she still struggled with empathy.

 

“Think they’ll break the record this time?” She asked, referring to the muffled voices coming from downstairs as she dug her phone out of her pocket. “My timer is at twenty minutes and counting.”

 

“Glad to know one of us is keeping track...” Frisk replied sarcastically while peeling back the foil protecting her gift. 

 

“You know, we don’t have to stick around for this. They wouldn’t notice if we disappeared for a little while.” Chara offered, popping another chocolate kiss in her mouth while tapping out a message. “Asriel wants to meet up at the mall.”

 

“Tempting...” She wasn’t going to lie. “How did he get out of prince training?”

 

“Asgore has a meeting with some foreign delegates. ‘Need-to-know basis’ kind of shit so Asriel can’t go.”

 

Frisk didn’t like taking off without letting Sans or Toriel know. The last thing she wanted was to make them worry and create even more stress, unlike Chara who lived for anarchy. That and she had homework to finish, plus she wanted to get a jump start on her study keys for finals.

 

When she only responded with a shrug, Chara propped herself up on her elbows and looked down at Frisk with pursed lips and a raised brow. This look asked if she really wanted to stay and listen to this crap on top of doing homework. After a long pause she replied with a soft snort and a slight smile, dragging herself out of bed to grab her shoes and some money from her Temmie bank.

 

By the time she was ready, the other girl was halfway out the window. They weren’t about to risk getting caught in the crossfire. Following behind Chara, Frisk worked her way quietly down the lattice that covered the wall of the house beneath her window. Fortunately both girls were light enough and with the flowered ivy to reinforce it, they could climb without fear of the wood giving out.

 

Once safely on the ground, they crept around to the rear of the house, ducking under the kitchen window as they made their way to the shed where their bikes were stored. Unlocking the chains with their respective keys, the sisters took off down the dirt road leading from the house to the main path through the forest. Both of them knew how to drive but there was no way they’d get away with taking Toriel’s minivan on top of sneaking out.

 

Hardly any cars drove this way, keeping the road fairly smooth and open to them. They wove back and forth, bursting into short races, and occasionally bumping each others tires. The further they rode the more they forgot what they were leaving behind. Out here there was no shouting, no arguing, and no tension. Just the rustling leaves, chirping birds, and the ‘whizz’ of their bike chains making natural music along with their laughter.

 

Frisk was going to miss this after graduation, having prepared herself to start college in the city right away. Chara said she was insane and Sans had even asked if she was sure that she didn’t want to take a break first. Nope. Frisk had decided not to be the type to wait, eager to move on to the next stage. Then once she had a degree or two under her belt she could go back to working on upholding monster equality.

 

Downtown wasn’t too far by bike. Within fifteen minutes, they were on the main road into the city and by sheer luck at each cross walk, found themselves at the mall shortly after. Asriel was waiting by the bike racks, waving excitedly as the girls pulled up and hugged them both before they had a chance to dismount. Once the monster prince’s growth spurt hit, his height nearly doubled excluding his horns. Unlike Chara, Frisk only got to see him every other weekend at their house and maybe once during the week if he had time to hang out. 

 

Every so often his appearance would startle her into a flashback of their battle, a split second were dark stripes would form on his furry white cheeks and the whites of his eyes would turn black, surrounding white glowing irises. She got the same feeling whenever Sans’s temper would flare and his right socket would darken while the left ignited with whispy blue light. They would both apologize profusely, being the only other ones aside from Chara who remembered all the timelines and battles and deaths it took for them to finally get to this point.

 

‘It will always be worth it though.’ She reminded herself as they walked into the mall together, one human on either side of their monster brother.

 

People didn’t stare as much anymore, if at all. It had taken years for this town to adapt after the monsters had emerged, many taking root in the area. Others fled as far from it as they could. She wasn’t technically their ambassador anymore, at least for the time being, but Asriel kept her updated on current events around the world. While the transition was slow, progress was being made and soon monsters would be allowed dual citizenship if not a full transfer into other countries around the world.

 

Their first stop was for cinnabunnies and bubble seatea. Frisk loved coming here for all the delicacies from the Underground. Muffet and Mettaton had started their franchises in this very food court, while the Tops, who did great business with his Nice Cream, preferred to keep to his little cart. Grillby had a burger stand here for a short while until he saved enough for a down payment on his own establishment. 

 

Sans had taken her there a few times and it looked and smelled exactly as it had back in Snowdin. Maybe she could convince him to take her there some time soon. Her birthday was coming up before the end of the school year and it had been far too long since she’d seen Grillby or had his incredible, yet greasy food. 

 

Taking their treats along, they popped into the anime store to check out the new stock. Frisk remembered the first time she brought Alphys and Undyne along. Finding out that anime wasn’t really real had been a great disappointment for the former Captain of the Royal Guard, but this place had made up for it quite a bit. The look of wonderment on their faces as they took in the shelves full of manga, dvds, and figurines, the bins full of plushies, and the racks of replica weaponry had been priceless. At least half of the store was bought out that day and it had taken more movie nights at their apartment than she could remember to get through the newly acquired collection.

 

Not finding anything new or interesting, the trio bought a few more snacks for home before moving onto the arcade. During breaks from school they would spend hours and much of their hard earned allowances here. This whole building had become one of their sanctuaries, where they could just be children instead of a prince, a problem child, and a savior. Until graduation at least, they could forget their responsibilities for a little bit longer.

 

A quick look at her phone told Frisk about two hours had passed since they left the house. No missed texts or calls meant either Toriel and Sans were still arguing or they just hadn’t checked on them yet. It was probably best if they took off soon. It wasn’t a popular suggestion, but Asriel at least agreed with her where as Chara couldn’t care less.

 

They hadn’t walked more than five feet from the arcade when a pair of security guards stepped up to them. One was younger, tall and lanky while the other was short, stocky, and had obviously been doing his job for a long time. If not for her sudden nervousness, Frisk would’ve laughed at how their size difference reminded her of Sans and Papyrus.

 

“Young lady. You’re gonna have to come with us.” The younger guard gestured to Chara.

 

Asriel and Frisk looked curiously at her initially unfazed and very uninterested expression.

 

“Why officers?” She responded in a bland tone, unable to keep herself from grinning then. “What seems to be the problem?”

 

“Don’t play dumb.” The shorter guard grumbled, his lips tightening beneath his nearly white mustache as he folded his broad arms over his chest. “The store owner turned in the security footage. Just hand over the weapon and come with us to call your parents.”

 

Weapon??

 

“Chara, you didn't…” Frisk almost groaned in exasperation.

 

She was used to dealing with her sister's kleptomania on top of her bad attitude, but this was taking it a step too far. A weapon made her an armed threat. She was lucky the cops weren't the ones stopping them. Especially because the look on her face right now was making Frisk increasingly more nervous.

 

“Oh. You mean…” The girl in question reached under the back of her shirt, putting the guards and her siblings on edge.

 

“This?...”

 

The blade of the ornate knife she produced was nearly as long as her forearm and wickedly sharp with a serrated edge. Frisk wondered how she’d even gotten it out of the store let alone kept it hidden afterwards.

 

“Alright. No funny business, kid.” The taller guard gestured to the floor, one hand on his tazer. “Put it on the floor and back away.”

 

“Hmm…And if I say no?” By now people were starting to stare and if Chara enjoyed anything aside from chocolate, it was putting on a show.

 

“Then you get tazed, cuffed, and we hand you over to the police.” The older man looked like he'd had enough and was already undoing the strap that kept the weapon belted.

 

“Come on, Chara…” Asriel pleaded, reaching out touch her shoulder and draw her attention. “Just listen to him so things won’t get any worse, okay?”

 

She took in her brother's soft gaze and sighed, crouching down to set the weapon on the floor and kick it away before turning around.

 

“You guys are so boring..” She huffed and started to walk away.

 

“Hey! Where do you think you're going!” The young guard stepped forward and caught her by the elbow.

 

“I wouldn't do that...”

 

“Chara please don't-!”

 

Frisk and Asriel sighed collectively as the man found himself on his backside with an aching crotch and bleeding nose. Nice to know she was utilizing her martial arts classes…

 

~~~~~~~~~~~~~~~

 

Sans had half a mind to just take off. He gave up on responding to Toriel's nagging long ago, but she still came back into his office every five or ten minutes to drive her point some more. If he wasn't already behind on grading papers and setting up the study guide for finals, he'd be at Grillby's right now.

 

He wished he could say he didn't know where things went wrong, but it was plain as the nonexistent nose on his face. The moment her other children came back into their lives, Toriel slowly ceased to be the adoring wife and dedicated mother she'd been to him and Frisk. 

 

He was understanding at first. At least in regards to Asriel. He was a good kid, smart, dependable, and he didn't cause trouble.

 

Frisk had told him all about how the late prince had become the golden flower that had rampaged across timelines long before she arrived, how her falling into the Underground somehow took his power to Save and Reset. She had tried to convince him to come with her and reunite with his parents on the surface, but he had refused, opting to stay away incase he forgot everything when he reverted back.

 

But it never happened. Alphys couldn’t even explain how he returned to his original body, or Chara for that matter.

 

The skeletons tired sockets narrowed and his broad line of teeth tightened.

 

Chara. The fucking monster that influenced Frisk into countless murderous rampages until she had taken over almost completely. The bitch didn’t deserve a second chance, mental disorder or not. She was pure evil and once again she was ruining his life.

 

Sans thought he was finally able to move on. No more timelines. No more resets. Frisk had given her word that she would never Reset again, even if she could, and he held her to that. Life had been great until She came back. 

 

Chara was a rogue element, violent and cruel. No amount of therapy was going to change that. Sans had stopped counting how many nights he spent consoling Frisk as a child, the complaints from other parents and the school board. She wasn't his kid but he still had to put up with the bullshit she caused on a nearly daily basis. 

 

Meanwhile, Toriel, his once loving wife, continued to make excuses for the hellion that had invaded their home. Even when she pushed Frisk down the stairs and broke her arm in two places, the former queen insisted that they all just needed time to adjust. Adjust his boney ass…

 

There was no ‘adjusting' to something like Chara. There was resentment, coping, then finally something akin to tolerance. He would never accept the beast that slaughtered his friends and family repeatedly, nearly driving him to the brink of insanity.

 

It had felt like years they'd spent repeating the same thing; monsters turning to dust, blood spilt over and over, Frisk’s eyes glowing red above a wide manic grin, Frisk's eyes filled with tears, vicious taunts, desperate pleas, dusty hands gripping a knife, arms open wide in surrender, crazed laughter, and pained cries…Again and again and again.

 

Toriel wouldn't understand. How could she? She thought he disliked Chara because of her connection to Asgore, that he resented her ex husband for being in their lives at all. How wrong she was. The only ones aside from him that truly knew what transpired during those dark times were the three children stuck in the middle of it all.

 

Groaning softly he dropped the red pen on the pile of papers scattered across his desk as he rubbed the sides of his skull. His controlled chaos. He used to love teaching, helping young minds expand in the sanctity of his classroom. Now he couldn’t even find peace there. 

 

Everyday during his last class, he looked out to his students and would find Frisk's weary face smiling at him. Seeing her there, looking as tired and emotionally drained as he was always brought him back to reality. His marriage was in shambles, his family in disarray, and his happy ending painfully short lived. These days he dreaded going home, opting to hide away at Grillby's and drink away the night.

 

He knew how much it hurt Frisk for him to be as absent as he had been lately, especially when Toriel was obviously playing favorites between them and her ‘first' family. It crushed him a little more every morning she shook him awake, hung over and still dressed in yesterdays clothes. She would still smile though, the faintest gleam of determination in her sad eyes as she said good morning with a cup of coffee in hand for him.

 

She didn't deserve all this. Not after how hard she fought to get them here and integrated back into human society. She didn’t deserve a mother who coddled a monster or a father figure who’d rather drown his anger and misery than spend another moment in the house he and Papyrus had built with their bare hands. Frisk had suffered enough; going through early childhood with no memory of the family that had abandoned her, to having the love and support of the entire monster kingdom as well as adopted parents who adored her, only to have the only real family she’d ever known broken down to…this.

 

Her stress was obvious. The sleeplessness, her loss of focus in class, the acting out. And it could all be traced back to Chara. Sans didn’t like that the human girls had bonded so closely. Granted Frisk had really needed a friend earlier on as human children had a penchant to be ruthless, taunting her for having monster parents because the human ones didn’t want her. She was still a good kid regardless, never causing trouble herself, but whenever Chara got herself into some shit, Frisk was almost always there to defend her...’sister’. 

 

One of these days that brat was going to get Frisk into real trouble.

 

“Sans!”

 

‘christ...here we go again...’

 

Those soft paws used to pad across the house so daintily. Now all they ever seemed to do was stomp around, more often than not towards his office.

 

“Sans! The-”

 

“look, toriel. i said i was done.” He didn’t regret cutting her off or even bothered to look up at her. “unlike you i have a ton of shit to catch up on. you’re so worried about frisk’s grades slipping then talk to her. i have almost a hundred other students i have to get prepped for finals week. so if you would ju-”

 

Massive white furred hands slammed down on his desk, startling him into finally looking at his enraged wife with narrowed sockets and fine glowing pinpricks. Her eyes, once so tender and loving, were wide and fearful, her brow drawn in tight as was the mouth that used to only ever smile for him. Whatever had her so panicked now didn’t have to do with their earlier shouting match, he assumed.

 

“Will you listen?!” The goat monster snapped, her claws scraping at the pages under her fingers. “The police just called. The kids are being held by mall security!”

 

“mall security?...” The fuck?… “they’re not in their rooms?”

 

“What do you think??” Toriel growled and rolled her eyes, stepping away from the desk. “Frisk’s bedroom window is open. They must’ve snuck out and took their bikes into town.”

 

“psh...you mean chara took frisk with her. you know she wouldn’t have-”

 

“Oh spare me, Sans! We have to go get them! Now!”

 

“...tch…shit...”

 

Groaning loudly, the skeleton pushed his rolling chair back and stood from the work he was going to have to put off yet again. Thank god it was Friday... Rounding the desk, he held out his hand for his wife, preparing to take a shortcut downtown. He stiffened when instead of feeling fur on his boney palm, her hand grasped at his shoulder. Cramming the offered hand into his pocket, he phased them away from their home and through the void into the city.

 

Within the hour they were back with the three children in tow, thanks to a few diplomatic threats from the former monster queen. Of course, they didn’t get off without repercussions; all three being banned from entering the mall without adult supervision until they turned 18, which at least for Frisk would be soon. Of course Chara challenged this and was immediately shot down.

 

“Chara. Asriel. At the table and wait until your father gets here.” She commanded sharply, usually soft eyes narrowed in anger. “Frisk. To your room. Finish your homework and don't come out for the rest of the night.”

 

“But I…” A boned hand on her shoulder stopped her protest as she turned to look at Sans.

 

Frisk felt her heart clench again, seeing the same look of disappointment still on his skull from when they'd first arrived to retrieve them from mall security. Chara had admitted her fault to keep her siblings from further consequence, but they had still been treated as accomplices until their guardians arrived and security footage was reviewed.

 

The cameras showed that Frisk and Asriel had been looking at some models near the weapons display Chara had been eyeing. The cashier that had been nearby, stepped aside to answer another customers question, giving the girl the opening she needed. After taking the knife they stayed in the store for several more minutes, collecting snacks and flipping through manga while the cashier and her siblings were none the wiser.

 

Toriel had given her older daughter a painful disappointed look that lasted only until Chara told her that the guard put his hand on her inappropriately. When the female monster demanded an explanation and proof, she nearly set the room on fire. The angle of that camera plus Frisk and Asriel's positions blocked direct view of the guard’s hands.

 

When the other children were questioned they sided indefinitely with their sister. Now with the claim of inappropriate contact with a minor and his partner threatening Chara with his weapon, they were able to compromise a ban instead of an arrest.

 

Sans, of course, didn’t believe a word of it.

 

“c'mon kiddo…let your mom handle them. you and me gotta talk…”

 

Heaving a defeated sigh, Frisk trudged up the stairs to her room, the skeleton following close behind. Once in her room she dumped her bag of treats on her desk before dropping onto the edge of her bed, bringing her legs up and crossing her ankles. She couldn't even look at Sans as he closed the door behind him, grabbing her rolling desk chair and sitting in it backwards with his arms folded atop the backrest.

 

Her fingers fidgeted with the charm bracelet Toriel had gotten her for her thirteenth birthday. Over the years she'd filled it with miscellaneous and custom-made charms (since Mettaton insisted she have one of his face..) to represent her loved ones. She swiped her fingertips over each one individually, letting them sway and jingle softly before stopping on a blue crystal bone and twisting it about. It had been a chance find and she almost didn’t buy it for the painful memories its shade brought on.

 

For a while after their move to the surface, Frisk would relive the timelines in her dreams, most nights crying in her sleep if not thrashing wildly from night terrors. Sans was there every time to pull her out of it, granted his face and blue magic holding her in place often triggered an even more terrified reaction. The skeleton started keeping vigil over her before she fell asleep, telling her stories about his and Papyrus’s childhood, giving words of encouragement, and telling her how proud he was for everything she’d overcome and was working so hard for.

 

The timelines eventually began to fade, still coming every so often but without leaving her a sobbing mess in the middle of the night. At least until Chara came.

 

When she moved in, the dreams went away all together, giving Frisk something to fear in the real world instead. But once they started to get along, it all stopped and she was finally able to sleep well at night. The other human seemed to be a curse and a godsend, bringing her a sense of kinship while simultaneously destroying her home life.

 

She couldn't even bring herself to hate Chara for it. The other girl had been an empty, hateful husk for so long and her mother didn’t want to acknowledge that she was potentially dangerous. She wasn’t aware of the events of the timelines like Sans and Frisk, but even without that knowledge she seemed to favor her first human child, at first if only to make up for Sans’s obviously dislike of her. She wasn’t neglectful in the least, but it soon became apparent that she longed for her previous life and family.

 

The first feeling of resentment towards the monster woman that cared for her was waved off as jealousy over Chara, but when the girls began to bond and things didn’t change Frisk started to lean towards her step father who was more than willing to dote on her in Toriel’s place. But soon even he cracked under the stress and opted to leave her, letting her strengthen the bond with the monster than haunted the dreams he used to chase away.

 

Frisk didn’t hate him for it either though. He’d been through so much while being aware of her as the anomaly, time rewinding back to her last Save each time she died or whenever she Reset, losing Papyrus and all of his friends countless times, having to kill her repeatedly. Now that they were on the surface, his happy ending was being picked apart piece by piece. Sometimes she wondered if he’d actually care if there was a Reset right now. Not that it was possible anyways. 

 

His own heavy sigh brought her out of her musing and she dared to glance up at him. His eyes were closed, chin resting on top of his arms with his mouth sitting straight. It seemed like he was asleep, especially with how harsh the creases beneath his sockets and at the sides of his mouth were. It still marveled her how expressive magic bones could be.

 

“kid...” The groan almost startled her. “we’ve known each other a long time right?...been through a lot?”

 

She nodded in response, regardless whether he was looking at her or not. He knew.

 

“your mom and i have raised you from a tiny little squirt to a young lady. i know all your tells and when you’re just trying to please the people around you...but you know, you should never feel the need to hide anything from me, right?”

 

Sans opened one eye halfway, the small white orb within pinning her down firmly but not threatening.

 

“i know i’ve been something like a parent to you for a long time, but...we’re still friends right?”

 

God her chest hurt so much...Only Sans could tug at her heart strings like that, even when she was a child. Whenever she had a bratty or overly shy moment with him, all he had to do was angle his brow just right then ask that same question and she was putty in his fused metacarpals.

 

Frisk nodded again, dropping her gaze back to her lap.

 

“and friends shouldn’t lie to each other. right?”

 

Another nod followed by another heavy sigh as Sans straightened himself.

 

“you really shouldn’t lie to your mom either...i know things have kinda sucked for a while now and chara isn’t exactly the best influence but-”

 

“Please...” Frisk’s voice hitched and she cleared her throat lightly, fingers working over time on her bracelet. “I know what she did was bad. She knows it too, but sometimes she can’t help herself. Asriel and I have been trying to help her, but Chara just has her days...This was a bad one I guess.”

 

There was silence for a while and she knew he was staring at her, obviously displeased. Sans hated being interrupted, especially when he was in ‘in-charge’ mode, like at school.

 

“see this is exactly what i’m talking about.” He huffed and pinched the bone above his nasal cavity. “you all have been coddling her. especially your mom. mental issues or not chara needs to learn to take responsibility for her actions or one of these days she’s gonna piss off the wrong person.”

 

She didn’t respond, instead folding her arms and turning her face away to glare at her dresser.

 

“or worse. she’ll get you and asriel in trouble. he’s the next king of monsters and needs to follow his dad in setting an example for us to mankind, not getting caught up in some shop lifting scandal...and her getting you to sneak out the house?...again? frisk, you know better than this.”

 

The human winced at hearing her name. Sans had always called her kid, kiddo, bud, buddy, pal, friend, or something else of the like. He usually only used her name when speaking of her to someone else or when he was proud or disappointed in her. There was no way to deny which it was now.

 

“You and mom were...busy.” She tried not to sound bitter, but it was so hard. “I couldn’t focus on my homework and it would’ve been...awkward...to just ask, considering what you were fighting about this time.”

 

Sans groaned in exasperation and sagged his shoulders as he stood from the chair and joined her on the bed. He reached out to tousle her hair familiarly then grabbed her shoulder to pull her close. She resisted stubbornly at first, but Sans always won this and eventually she was tucked against his side, her head resting against his collarbone. His magic made his bones warm and created a kind of cushioning that kept his clothing from just hanging off his body awkwardly, resolving her curiosity of how a skeleton could be...pudgy. Through the button up shirt he’d yet to take off from work, she could feel the steady pulse of his soul, similar to a human heartbeat.

 

“look i...we’re sorry.” Sans huffed, squeezing her shoulder and tilting his head to rest on top of hers. “we know its hard for you...and we’ve been trying to work on it but...your mom and I don’t really see eye to socket anymore. between chara getting herself into mess after mess and...how your grades are slipping this year and the acting out-”

 

“I have not been-”

 

“can it, frisk.” The harsh tone and tightening grip made her flinch. “you’re not as focused in school as you used to be and you’ve been getting snippy with your mom...and me. there’s only two months left for the school year and in three weeks you’ll be an adult. if you nail these finals, like i know you can, you’ll get that scholarship you’ve been busting your ass for.”

 

He wasn’t wrong. She’d walked into high school and continued her junior high streak of straight A’s, even in her advanced classes. She was always first to volunteer for events and was on the student council before she finished freshman year. The staff adored her and ever since Chara kicked some jocks teeth in for picking on them for having monster parents, no one bothered her.

 

Like the mall, school had become a sort of haven away from the stressful atmosphere at home…at least for a little while.

 

“you won’t have to worry about tuition for college and with the money you’ve got saved you can go stay in some student housing if you really wanted to. i know your mom wont like it...hell I dont like the idea of being stuck here without you either...but if that’s what you need to do when the time comes then go for it. seize the day. manifest destiny and all that crap.”

 

Frisk snorted quietly, finding the idea of leaving him behind for any reason...distressing. 

 

When the winter of her junior year came around, the fighting had gotten worse. Toriel had insisted they accept Asgore’s invitation to take a vacation for the Christmas holiday. Sans had been livid, not only because they’d already made plans to spend Christmas Eve with Asgore for the kids then see Papyrus the next day, but because she waited until the week before to say anything. It only pissed him off more when she took Chara and went anyway, leaving him and Frisk to celebrate Christmas morning alone before meeting up with everyone else at Mettaton’s party.

 

They had a wonderful time of course, but the hurt was evident in the amount of spiked egg nog Sans had downed that night. He’d even snuck her a cup or two with the promise she wouldn’t say anything to her mother, unless she wanted to have a ‘baaah’-d time. It had been so long since she’d laughed like that, she’d been afraid she wouldn’t be able to stop until egg nog came out her nose.

 

The rest of the night had been a blur of music, dancing, and laughter...and who could forget the ‘Metta-Clause’ shaped Christmas fare? But since that night Frisk hadn’t been able to push what happened after they went home out of her mind. It had been so innocent, but it stirred feelings within her she knew were so much less than pure.

 

Sans's arm had been draped around her shoulders, bearing his weight against her less than stable form as they materialized in the living room of their empty home. Guided only by their spacial memory and the glittering lights of the Christmas tree in the corner, they found their way to the couch. Specifically Sans’s leg found it first, throwing both of them even more off balance and sending them tumbling down onto the plush cushions decorated with holiday throw pillows and a handmade quilt. They giggled like fools as they tried to untangle themselves, giving up quickly in favor of just crashing there.

 

When morning came Frisk had been the first to wake, her mind still fuzzy and aching just a bit. Her neck was sore too, but when she tried to shift to roll over she found herself pinned in place with a firm weight across her waist and settled between her thighs. There had been a moment of panic, but the skeleton’s familiar snoring relieved her fear. He’d tucked her close against his rib cage, one arm keeping an embroidered pillow in place for her head while the other wrapped around to keep her from falling off the couch. She could feel the faintest temperature difference as his hand had found its way up the back of her sweater, the tips of his phalanges cradling the small of her back.

 

It wouldn’t have been a big deal. They’d fallen asleep together hundreds of times over the years. On the couch, his recliner, the floor, and even on the grass in the backyard. Napping had been one of their favorite pastimes…But they usually weren’t pressed this close and certainly not with his femur wedged right at the apex of her thighs. The last thing she expected was when she’d tried to move again, the firm bone of his knee nudged her core, eliciting an intense sensation she wasn’t all that unfamiliar with.

 

With her mind still addled somewhat by her first taste of alcohol, she’d checked to see if he’d woken up before tentatively wiggling her hips a few times for more contact. She was a young, developing woman, still learning about her own body and what it was capable of. In that moment, she didn’t fully consider what she was doing or who with. A quiet moan had barely formed in her throat before the grip around her waist tightened and pulled her even closer, Sans’s barely audible voice grumbling to ask if she was cold snapping her back into reality.

 

At first Frisk had felt mortified and disgusted with her body for reacting in such a way. Sans was the closest thing she’d had to a father. He’d protected, raised, and supported her for most of her life. He was her best friend, mentor, and not to mention her adoptive mother’s husband...It was so so wrong to think of him as anything more than that…

 

But she hadn’t felt the same about him or anything else since that morning...and she was so...so curious. 

 

From that point on her focus began to slip. Between the stress at home and her conflicting emotions regarding her ‘step father’/science teacher, the clubs and after school activities fell to the wayside. The first time any of her grades dipped below an A-, she had been devastated, invoking a month of cramming on extra credit to get it back up again. The look of disappointment on Toriel’s face and Sans’s confusion had been too much to bear. She was terrified of letting them down, at that point feeling as though they were only staying together for her and that if she failed them in any way...if she wasn’t perfect to make up for Chara’s short comings, they were doomed to finally end it.

 

Frisk was a smart girl and incredibly efficient in her work. She could memorize equations and algorithms so well and Sans couldn’t have been more proud. The only thing she ever got teased for was being the teacher’s pet and even that was just in fun. Eventually the weight of it became to much to bear too. She could get a passing grade in her sleep, but the motivation to use her full potential was gone. And with that, so was the hope that she could keep her family together.

 

They were just going through the motions at this point. The only time she felt at ease anymore was with Chara and Asriel, when she could forget about everything and just be a kid again for a while. 

 

What was going to happen to them in the next few months? Graduation was coming far too quickly...

 

“but until that day you cross the stage with your diploma in hand, you need to crack down and stop letting chara influence you like this...that time was over the moment you told her no more and fought back. i get that you made some terrible decisions back then too, but you turned around and did the right thing. you need to let her learn that for herself, even if the outcome doesn’t end up good for her. you, her brother, and their parents can’t keep enabling her behavior.”

 

When she didn’t respond, Sans chanced a look down at her face, instantly regretting it. She looked so tired and forlorn, much like his own reflection these days. He didn’t want to be so firm with her, but he wasn’t going to let her waste the opportunity she had to make something of herself. He wasn’t going to let Chara take anything else from Frisk.

 

Heaving another sigh, he hugged her closer and reached over to tilt her head up to look at him. For a second he swore her cheeks had flushed, but he disregarded it.

 

“i know its in your nature to be kind and selfless, kid...but this is your future we’re talking about here. at some point you’re gonna have to start worrying about yourself and not people who don’t even wanna help themselves.”

 

The human girl he’d taken care of for years closed her eyes to him, her lips parting just enough to pull the bottom one in with her teeth. She tilted her head down and pressed her brow into his collarbone, twisting her body towards him to loop her arms around his torso. Sans returned the embrace, resting his chin on top of her head while stroking her hair. He knew she was trying not to cry, could feel the heat of her heavy breaths through his shirt and the trembling of her shoulders. 

 

She hadn’t cried in front of him in years, but he knew she did fairly often, having passed by her room late at night and heard the quiet sniffling from inside on more than a few occasions. He always had to fight the urge to walk in and gather her up, to hold her close like this and tell her everything would be alright as he had when she was little. He refused to lie to her though. Even now as she fought to keep her sobs in the skeleton stayed silent, twisting locks of her hair through his phalanges and taking in the faint scent of her shampoo. 

 

“I just...I thought if I tried...really hard...” Her voice hitched and she shuddered away another sob. “...maybe I could help her to be...better…then you wouldn’t hate her anymore...and we could be a family again...”

 

Air rushed through his nasal cavity in a heavy sigh, rustling her hair. Of course she would blame herself. Even after bringing down the barrier, Frisk had worked so hard to make sure the struggle had been worth it, in her own home as well as for monster-kind. Anytime something didn’t go as planned, she’d blame herself for not working hard enough for it. She’d spent god knows how long underground Saving, Loading, and Resetting until she finally got it right.

 

Now on the surface, without her power, there was no more do overs. She just had to take the results as they came no matter if she was satisfied or not. It had been hard at first when she was still young, but eventually she came to terms with it. Not to say that it didn’t still hurt so see her so broken up over it.

 

“look kid...your mom and i...” Sans huffed and pulled her even closer until she draped her legs over his femur like when she was still small. “we've just…grown apart...we had a great run, but maybe we weren’t meant to last forever after all. i've started to think our relationships outlived its purpose...that maybe we were only supposed to be together because you deserved a family after everything...and you do...you deserved that and so much more, kid.”

 

The boney fingers in her hair pressed her head more firmly into his clavicle as more hiccups shook her body. They were starting to shake too, the tips scratching lightly at her scalp and nape of her neck.

 

“i tried pal...but there’s only so much that can be said and done...so much im willing to ignore...” The skeleton huffed again, his hands shifting to grasp Frisk’s shoulders and lean her back enough to see her face. “you’ve always been stronger than me, than any of us, and not just because of your determination...i didn’t want to give up because i know how much it means to you that your mom and i work this out...but….its probably time to just throw in the towel.”

 

His soul shuddered at the sight of her tears falling and the broken sound that finally escaped her, his hands moving up to cup her face. It wasn’t as round as it had been when she was little, but the skin was still soft and warm under his bones.

 

“hey hey hey...i know it hurts, but its for the best. understand?...”His own sockets were starting to ache and burn as he wiped the clear drops away with his thumbs, leaning in to press his forehead to hers. “i'm not gonna just disappear. i’ll always be there no matter what...this mess that your mom and i got going on right now is not gonna change that.”

 

With their faces this close and vision distorted, he could still see her distraught, unbelieving expression and sighed. Grunting softly as he gently shifted her from his lap, the skeleton moved to kneel beside the bed. His hands slid down from her shoulders and over her arms to grasp her hands, not willing to break contact and risk hurting her more. The desperate way she clung to his own hands was soul-wrenching…

 

“call me. anytime. anywhere. i don't care if it’s in the middle of class, early morning, or late at night. i know i shouldn’t even have to make that offer but i also know i’ve been letting you down a lot lately and i cant be sorry enough…”

 

When Frisk opened her quivering lips to argue, he slipped a hand free to hush her. Rigid bone brushed away more sad droplets, not getting the chance to pull back before being covered by delicate human fingers. The girl nuzzled into the skeleton’s palm, eyes barely open and spilling more tears as the opposite pair still clutched together.

 

“you know I hate making promises kiddo, so I’m gonna ask for one in return.” The hand on her cheek slid to her chin, using it to direct her gaze back to his while her grasp slipped down to his wrist. “keep me in check and make me hold up my end. i don’t care if you think you’re being annoying or if i’m busy with something. i’m all yours whenever you need me…”

 

Frisk’s smile was weak and watery, but she tried her best and nodded. Sans’ usual grin returned, wide and comical yet relieved as he freed his hands to stand and embrace his human charge. She shifted closer to the edge of the mattress to return the hold, her fingers hooking into the back of his ribs just below his shoulder blades. The slight stiffening of bone went unnoticed in place of the warm chuckle that vibrated the clavicle and ribcage she leaned into.

 

“hehe…that’s my girl.”

 

It wasn't a fix-all, but it’s what Frisk needed right now; a tight hug and a promise from her best friend. It hurt more than anything to know that he was giving up, but he was exhausted, hurting and she couldn't blame him for it. To expect him to endure anymore just for her sake would be no better than forcing him through another Reset. It was selfish and it was cruel...and she’d made a promise to herself that she would never hurt him or anyone else she loved again.

 

All too soon there was a gentle knock at the door, breaking the soothing calm that had finally settled between them. Sans huffed, giving Frisk another tight squeeze and ruffling her hair before leaning away. His grin was strained, but he was trying and she appreciated that even more now.

 

“That'll be your mom…” He didn’t mean to sound bitter, at least not in front of her. “Keep your chin up, kiddo. Remember, anytime for any reason alright.”

 

Brushing her bangs aside, he pressed his teeth to her forehead, a spark of magic tickling her skin. Her face warmed and she was sure he saw it in her cheeks if the broadening smirk told her anything.

 

“hehe…see ya later, alligator.”

 

“After a while, crocodile…”

 

That seemed to brighten him up as her turned and made for the door. He paused as if to brace himself before grasping the knob and stepping aside to let his wife in. The goat monster glanced down at the skeleton, brow raised. She was holding a plate in her paws, heaped with the dinner she'd been preparing before the call. Sans just shrugged casually as he moved past her, closing the door behind him.

 

A wave of exhaustion hit him, bringing him to lean heavily against the wall outside Frisk’s room. He heard the pair inside speaking softly, unable to make out their words, but at least Toriel wasn’t ripping her a new one. He couldn't handle another fight today…

 

For a while he debated going to Grillby's and finishing the rest of his work tomorrow while the kids had a study day. After a few moments he shambled off to his office anyways, reminding himself that his students and especially Frisk were depending on him to make it through the rest of the school year.

 

He could make it two more months right? Hell, grading finals would be a cake walk compared to filing divorce papers…

 

~~~~~~~~~~

**Author's Note:**

> I had told myself I wasn't going to post this until I finished my other Undertale fic, but I've been so stuck with it I figured why not. 
> 
> Hope you enjoyed it! No promises on when the next chapter will be out though...Sorry...Adulting sucks @×@...
> 
> FYI the title might change but my husband is insistent that I keep it XD


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